Breast cancer screening by mammography is part of routine wellness care for women starting at around age 40 in the United States. 40 million women are screened annually with mammograms to detect the ~250,000 new cases of breast cancer that occur each year. Mammograms still miss 15% of cancers, and sensitivity falls to 45-50% in women with high density breasts, which is more common in younger women. High breast density is itself considered a risk factor for breast cancer (BC), and the FDA has declared managing breast density information a major policy goal for 2018. More women are also now identified as at high risk for breast cancer with commonly available genetic testing. Detection of breast cancer at its earliest, curable stages is precisely when imaged based screening methods are more likely fail. Imaging methods clearly play an important role in early BC detection, providing structural information about the tumor, but are not fail proof, and would benefit from complementary screening tools, especially in cases where imaging is more likely to fail (younger women, high breast density). Precision medicine approaches and liquid biopsies have the potential to transform cancer detection and management. Saliva is a noninvasive biofluid that contains functional biomarkers, including RNA, protein and metabolites. Biomarkers for many diseases have been identified in saliva, including breast cancer. As a screening method, saliva sampling is noninvasive and easy to collect, and compatible with procedures at the point-of-care, such as at breast imaging clinics. To date, saliva based diagnostic efforts have largely been undertaken in academia, without a comprehensive industry-initiated approach for product development and commercialization. In this phase 1 project, ?A Noninvasive, Precision Medicine Approach to Improve Breast Cancer Screening Using Cell-free RNA from Saliva,? we propose to develop the first saliva-based companion screening diagnostic for BC. Our prototype test called CertinaTM was developed by applying our proprietary and novel algorithmic approach to gene expression microarray data from saliva collected from BC patients and has been validated in two separate clinical cohorts. Our initial 9-gene signature has an 83% sensitivity and 90% specificity for invasive BC detection. In this phase 1 project, our objectives are to develop a saliva collection kit optimized for collection of our signature RNA, with room temperature stability for collection and transport, with our partner Oasis Diagnostics, a leader in the field of saliva collection devices; establish a saliva biobank for BC assay validation, partnering with Cancer Research Collaborations in Southern California to collect a wide range of clinical samples for longitudinal studies and for use in assay improvement; assess the accuracy of our signature in early stage breast cancer and in women with dense breasts, as well as improve performance of the CertinaTM assay. Completing these objectives will provide the tools for a Phase II large-scale study, pairing our test with primary screening in breast cancer as the first saliva-based commercial diagnostic for breast cancer.